This invention relates to a power inlet arrangement for providing power to the electric system of a building, such as power supplied by a standby generator.
Portable generators may be used in certain situations to feed electrical power to residential and commercial load circuits during a utility power outage. These systems frequently include a power inlet box adapted for interconnection with the generator. The power inlet box is typically mounted to the exterior of a building. The power inlet box is connected to a transfer switching mechanism which continues the electrical path through circuit breakers associated with the transfer switching mechanism, to supply power to certain selected circuits of the load center as determined by the transfer switching mechanism circuit breakers. The circuits of the transfer switching mechanism are wired to selected circuits of the load center, through wiring housed within a conduit extending between the load center and the transfer switching mechanism.
The present invention relates to a power transfer arrangement such as is disclosed in co-pending U.S. patent application Ser. No. 09/021,670, filed Feb. 10, 1998, the disclosure of which is hereby incorporated by reference. In that application, a power transfer switching mechanism for interposition between a remote power inlet box and the electrical load center of a building includes a terminal compartment for receiving power input wires connected to the remote power inlet box. The switching mechanism includes a cabinet defining an internal cavity within which a series of switches are mounted. The cabinet further defines a terminal compartment, and a terminal assembly is disposed within the terminal compartment. The terminal compartment is accessible through an opening associated with the cabinet, and a cover is selectively positionable over the opening to provide or prevent access to the terminal compartment. A series of wires are interconnected between the terminal assembly and the switches, and power input wiring is received within the terminal compartment and interconnected with the remote power inlet box. The ends of the power input wires are engageable with the terminal assembly for establishing a direct electrical connection between the remote power inlet box and the switches of the switching mechanism.
The present invention also relates to a power transfer switching mechanism such as is disclosed in co-pending U.S. patent application Ser. No. 09/062,257, filed Apr. 17, 1998, the disclosure of which is hereby incorporated by reference. The '257 application improves upon the '670 application by disclosing a power input terminal arrangement in the power transfer switching mechanism in combination with a removable cover for preventing access to the power input terminal arrangement. The cover is provided with a power input structure, such as a socket or receptacle, connected to the terminal assembly for selectively receiving a plug connector electrically interconnected with a source of auxiliary power such as a generator. The power transfer switching mechanism in the '257 application provides a selective rather than a direct, hardwired electrical connection between the remote power inlet box and the switches of the switching mechanism.
While the above-described transfer switching mechanisms provide extremely convenient and simple arrangements for establishing direct, hardwired and selective connections with the power inlet box, it is sometimes desirable to provide a power transfer switching mechanism having a power input meter arrangement in its front panel. With this modification, it is possible to monitor the amount of power provided by a generator during a power outage, so as to prevent overloading of and subsequent damage to the generator or to the building electrical system. Although the broad concept of integrally providing power input meters on a power transfer switching mechanism is well known, it is desirable to modify the power transfer switching mechanisms described in the aforementioned co-pending patent applications to provide an optional meter arrangement in a cover which is selectively engageable with the cabinet of the switching mechanism.
It is an object of the present invention to provide a transfer switching mechanism having a removable access cover provided with a power input meter arrangement for measuring input power to the transfer switching mechanism from a generator or from a power inlet connected with the generator. It is a further object of the present invention to provide such a transfer switching mechanism which ensures that a reliable selective connection is established with the generator when power is supplied to a transfer switching mechanism. Another object of the present invention is to provide a transfer switching mechanism which is simple to install and which operates generally similarly to prior art transfer switching mechanisms. It is also an object of the present invention to provide a method for constructing a power transfer device having interchangeable access covers, one of which functions as an optional meter panel for monitoring power supplied by a generator so as to prevent overloading thereof.
The invention contemplates an improvement in a power transfer arrangement for supplying power from a generator to the electrical system of a building. The power transfer arrangement includes a power inlet arrangement for interconnection with the generator for receiving power therefrom, and a power transfer device separate from the power inlet arrangement adapted for interconnection with the building electrical system. The invention resides in a power input terminal arrangement in the power transfer device in combination with a removable cover associated with the power transfer device for selectively preventing access to the power input terminal arrangement. The cover is provided with a power input indicating structure connected to the power input terminal arrangement for selectively displaying the amount of power provided by the generator. The power transfer device includes a cabinet having a front panel to which is mounted a set of switches for controlling the supply of power from the power transfer device to the building electrical system, and the set of switches are electrically connected to the power input terminal arrangement. The power transfer device further includes a set of power input terminals for establishing a direct electrical connection between the power inlet arrangement and the power transfer device. The power input terminals are located within a power input terminal compartment defined by the cabinet at a location spaced from the set of switches. The cabinet defines an opening providing access to the power input terminal compartment. The cover is positionable over the opening and removably engageable with the cabinet for selectively closing the opening for preventing access to the power input terminal compartment. The opening providing access to the power input terminal compartment is defined in part by a rearwardly extending edge of the front panel. The cover has a rearwardly extending ledge engageable with the rearwardly extending edge of the front panel, and a vertically extending wall depending from the edge and engageable with an end wall of the cabinet. The ledge is recessed to accommodate the power input terminals when the cover is in position covering the opening. The power input indicating structure is fixed to the vertically extending wall of the cover. The power input indicating structure includes at least one meter have a block-like rear portion and convexly-shaped forward portion projecting through the vertically extending wall of the cover. The forward portion includes a transparent window having a support member for mounting a wattage scale visible through the window, and an indicator mounted for movement along the scale in response to the supplying of power from the generator.
In the preferred embodiment, the power input indicating structure includes a pair of spaced apart meters. Each of the meters is fixed to the vertically extending wall of the cover by a spring-biased clip. The power transfer device also includes a set of power input wires extending between the power input indicating structure and the power input terminals. The power indicating structure includes a U-shaped attachment bracket positioned on the vertically extending wall of the cover for facilitating connection of the meters to the power input terminals. The attachment bracket includes a flat base plate and a pair of parallel side plates extending rearwardly from the base plate. An H-shaped terminal connector is fixed to the base plate and a pair of wire-guiding holders are fixed in the side plates.
The invention further contemplates an improvement in a power transfer device adapted for interconnection with the electrical system of a building and including a cabinet, a set of switches mounted to the cabinet, and a first set of wires connecting the switches to an electrical distribution panel associated with the building electrical system. The invention is in the form of a terminal compartment associated with the cabinet, a set of power input terminals located within the terminal compartment, and a cover removably connected to the cabinet for alternately preventing and permitting access to the terminal compartment. The cover is provided with a meter arrangement interconnected with the power input terminals and adapted to selectively measure levels of power provided from a source of auxiliary power connected to the power input terminals. A set of power input wires enables connection of the meter arrangement with the power input terminals. The power input terminals are connected to the switches by a second set of wires. The cabinet includes a set of tabs spaced along an end wall thereof, the tabs having apertures formed therein. The cover includes a set of openings alignable with the apertures in the tabs. A set of fasteners is passed through the openings in the cover and is threadably engageable with the apertures in the tab.
The invention also relates to a method for constructing a power transfer device for supplying power to the electrical system of a building from a generator in electrical communication with a separate power inlet arrangement. The method includes the step of providing a cabinet having a power terminal arrangement; equiping the cabinet with a panel including a plurality of switches electrically connected to the power input terminal arrangement for controlling the supply of power from the power transfer device to the building electrical system; providing a first cover member adapted for removable engagement with the cabinet over the compartment for selectively enclosing the power input terminal arrangement; providing a second cover member having a power input meter arrangement and adapted for removable engagement with the cabinet over the compartment for selectively enclosing the power input terminal arrangement; and mounting either the first cover member or the second cover member to the cabinet over the compartment. The step of mounting the second cover member includes interconnecting the power input meter arrangement with the power input terminal arrangement.
Various other features, objects and advantages of the invention will be made apparent from the following description taken together with the drawings.